STORY ARCHIVE

Biggest Devonian Fish

TRANSCRIPT

Known as the "Age of the Fishes", the Devonian Period also marks the time the first vertebrate animals crawled onto land. Paul Willis goes fishing on the south-east coast of Australia, where researchers have discovered the fossilised remains of the biggest Devonian fish ever found.

Dr Gavin YoungG'day Paul.

Dr Paul WillisLong time no see, mate.

Dr Gavin YoungYeah, good to see you.

NARRATIONToday I'm being taken to a secret fishing spot on the New South Wales South Coast. But I won't need a rod and reel.

Dr Gavin YoungWe're actually walking down a bedding plain here. It would have been a flat floodplain near a big river.

NARRATIONBack when Australia and New Zealand were part of the massive supercontinent Gondwana, this area was situated in a big rift valley between the two. These striking red layers of mudstone were laid down hundreds of millions of years ago - long before dinosaurs walked the earth. Known as the Age of the Fishes, the Devonian period also marks the time the first backboned animals crawled onto land.

Dr Gavin YoungThe other thing that was happening at that time, which is fundamentally important in the history of the planet - the very first forests evolved during the middle part of the Devonian period. So we had lakes, we had rivers, we had a forested environment, we had animals living on the land, and we also had teeming fish in all the water bodies. A very vibrant place, with all sorts of things happening in terms of evolutionary process.

NARRATIONAnd this is one of the best spots in the world to see the evidence.

Dr Gavin YoungWow, look at this stuff.

Dr Paul WillisIt's fantastic.

NARRATIONArmoured fish bones are preserved with incredible detail. Remnants of smaller bony fish litter the landscape. But nothing prepared Gavin's team for what lay above.

Dr Gavin YoungThere you go, Paul. We found this enormous fang.

Dr Paul WillisThat's huge.

Dr Gavin YoungThis indicated that there was another fish preserved in the rock, a very big animal, the top predator in this particular region.

NARRATIONEmbedded in the rock layers below their feet lay a monster lobe-finned fish, around five metres long. It took rock saws, drills and three separate expeditions to remove the enormous fish skull, in bits and pieces. The result is a massive three-dimensional jigsaw puzzle, which will take years to put back together.

Dr Gavin YoungIsn't this the bit where we've got the two teeth, rows of teeth together?

ManYes.

Dr Gavin YoungInterlocking?

ManWe have.

Dr Paul WillisIs this the biggest fish you've ever found?

Dr Gavin YoungAh, I think in terms of fossil fish, this would be, I think perhaps the biggest thing that we've ever found. It also seems to be the biggest lobe-finned fish known from anywhere in the world that is actually articulated together.

NARRATIONLobe-finned fish had hard bones inside their fins, and could essentially do push-ups - one of the first steps to moving out of the water and onto the land. So this fossil find represents a transitional species in the evolution of land animals like us.

Dr Paul WillisNow obviously there's a lot of interesting stuff going on here. There are bones all over the place, but I can't make head nor tail of it. Time to bring in a bit of high technology.

NARRATIONSurface scanning can reveal the outer surfaces of the fossil, allowing the animal's external structure to gradually be pieced together using special software. But the investigation can also go internal, using x-rays. This is not the fish skull from Eden, but this three-dimensional scan shows the kind of detail that can be revealed by combining the two techniques.

Professor Tim SendenThe x-ray technique will allow us to understand a bit more about the biology of the animal itself. It's very fragmentary, um, but certain elements of it we will be able to scan at this sort of resolution.

NARRATIONAnd this is the first 3D scan of the big catch - a fang from the biggest Devonian lobe-finned fish ever found. As the rest is pieced together, the big question is, what's this new species called?

Dr Gavin YoungIt's from near Eden on the South Coast, so we think Edenopteron will be a nice name. So that at the moment is an informal name.